It certainly is possible. In order to insure a fairly rapid erasure, you
must be within 10,000 kilometers of the sun. Um, I think you want the Moon
Rocket project mail exchange list.

If you go to the trouble, let folks know so that we can mount our windowed
parts to be erased to the rocket as well, since you are going to all of the
trouble. Seems a pity to make the journey for one part.

>Hi
>Is it possible to erase a windowed PIC with sun light ??
>How much do I have to wait ?
>Bye and thanks
>
>Javier
>PD I just bought a 12c509 shouldn4t it be erased ?

At 15:06 24/09/99 +1000, you wrote:
>At 02:22 23/09/99 -0300, you wrote:
>>Hi
>>Is it possible to erase a windowed PIC with sun light ??
>>How much do I have to wait ?
>
>Weeks I would say. Not good for your development cycle time.
>

>Is it possible to erase a windowed PIC with sun light ??
>How much do I have to wait ?
>Bye and thanks

Yes, it is possible. For EPROMs (27xxx series), some datasheets state that
erasure in the sun requires 1 week of constant direct exposure. I left a AMD
2732 EPROM in a south facing window for 2 months, and nothing changed. An
intel datasheet says "constant exposure to room level fluorescent lighting
could erase the EPROM in approximately 3 years."

I finally broke down and bought a $150 canadian EPROM eraser, that can eat
about 20 EPROMs at a time, meaning about 80 8 pin PICs at a time.

Hi,
your experiment was unsuccessfull, because of normal window glasses filter
the UV component out. That's why EPROM's have special quartz window. A
direct exposure can tamper the EPROM's content in less than one hour I
guess (at least at us, in a Summer Noon).

> >Is it possible to erase a windowed PIC with sun light ??
> >How much do I have to wait ?
> >Bye and thanks
>
> Yes, it is possible. For EPROMs (27xxx series), some datasheets state that
> erasure in the sun requires 1 week of constant direct exposure. I left a AMD
> 2732 EPROM in a south facing window for 2 months, and nothing changed. An
> intel datasheet says "constant exposure to room level fluorescent lighting
> could erase the EPROM in approximately 3 years."
>
> I finally broke down and bought a $150 canadian EPROM eraser, that can eat
> about 20 EPROMs at a time, meaning about 80 8 pin PICs at a time.
>
> If you are looking for alternative erasure methods, have a look at:
> http://www.intermarket.net/~don/uvbulb.html
>
> - Keelan Lightfoot
>
>

>Hi,
>your experiment was unsuccessfull, because of normal window glasses filter
>the UV component out. That's why EPROM's have special quartz window. A
>direct exposure can tamper the EPROM's content in less than one hour I
>guess (at least at us, in a Summer Noon).

In Canada? Hehe :)

I guess I'll have to replace all the windows in my house with quartz glass
:)

> Yes, it is possible. For EPROMs (27xxx series), some datasheets state that
> erasure in the sun requires 1 week of constant direct exposure. I left a AMD
> 2732 EPROM in a south facing window for 2 months, and nothing changed. An
> intel datasheet says "constant exposure to room level fluorescent lighting
> could erase the EPROM in approximately 3 years."

Even if you put the eprom outside (no window glass UV filtering at all),
you need to clean the eprom quartz window daily, since moisture and
dirty works as UV filters as well, not talking about bird droppings...
:)

At 02:22 AM 9/23/99 -0300, Javier wrote:
>Hi
>Is it possible to erase a windowed PIC with sun light ??
>How much do I have to wait ?

I think this is more doable than the others.

Since you can can expose a PC board with 4-8 hrs of sunlight, and that
requires UV-A, I would think that it should also work for EPROM, which
requires only a longer wavelength UV.

Make sure you don't block the sun with a window or other covering. Expose
for 4 hrs. Do an erase check and see if bits remain that still unchanged.
If the number of bits is very large (e.g, > 50%), then it's hopeless. If
they're few (< 10%), expose for another 4 hrs.

Let us know what happens.

PS. You don't need to get 10,000 km from the sun on a rocket. Just getting
out of the earth's atmosphere should do nicely. Of course, if you had
EPROMs strapped to a Mars probe, you can kiss those babies goodbye now!

At 11:58 PM 9/23/99 -0700, Keenan wrote:
>Yes, it is possible. For EPROMs (27xxx series), some datasheets state that
>erasure in the sun requires 1 week of constant direct exposure. I left a AMD
>2732 EPROM in a south facing window for 2 months, and nothing changed. An
>intel datasheet says "constant exposure to room level fluorescent lighting
>could erase the EPROM in approximately 3 years."

Glass is a pretty good absorber of short wavelengths. You need to place the
chip in the direct sunlight.

You could possibly filter the IR with a quartz window and then collimate
the sunlight with a lens.

All of this presupposes a dry, equatorial climate with lots of W/sq. m.

PS. I gave the wrong UV type in the last post. UV-C is the short wavelength
stuff.

At 09:09 AM 9/26/99 +1000, Paul wrote:
>> You could possibly filter the IR with a quartz window and then
>> collimate the sunlight with a lens.
>
> Now where would you get such a thing? A solid fuzed quartz lens?

Sure. Take a large piece of quartz, and grind it down with carborundum or
silicon carbide grit.

A simpler method would be to mount the eprom in a parabolic reflector.
Perhaps an old headlight reflector or large flashlight reflector would
work. Or you could make one out of aluminum foil.

What ever happened to the old.."magnifying lens trick " not a pin point
... but a little wider than the window? Take the chip ......
antistatic foam on a piece of card board.......make mounting for lens..
rotate often........well done in 2 hrs............anyone cooking
out?......will supply beef ribs..
{Original Message removed}

>Hi,
>your experiment was unsuccessfull, because of normal window glasses filter
>the UV component out. That's why EPROM's have special quartz window. A
>direct exposure can tamper the EPROM's content in less than one hour I
>guess (at least at us, in a Summer Noon).
>
>Regards,
>Imre
>
>
>On Thu, 23 Sep 1999, Keelan Lightfoot wrote:
>
>> >Is it possible to erase a windowed PIC with sun light ??
>> >How much do I have to wait ?
>> >Bye and thanks
>>
>> Yes, it is possible. For EPROMs (27xxx series), some datasheets state

that
>> erasure in the sun requires 1 week of constant direct exposure. I left a
AMD
>> 2732 EPROM in a south facing window for 2 months, and nothing changed. An
>> intel datasheet says "constant exposure to room level fluorescent
lighting
>> could erase the EPROM in approximately 3 years."
>>
>> I finally broke down and bought a $150 canadian EPROM eraser, that can
eat
>> about 20 EPROMs at a time, meaning about 80 8 pin PICs at a time.
>>
>> If you are looking for alternative erasure methods, have a look at:
>> http://www.intermarket.net/~don/uvbulb.html
>>
>> - Keelan Lightfoot
>>
>>